Welcome to HVAC-Talk.com, a non-DIY site and the ultimate Source for HVAC Information & Knowledge Sharing for the industry professional! Here you can join over 150,000 HVAC Professionals & enthusiasts from around the world discussing all things related to HVAC/R. You are currently viewing as a NON-REGISTERED guest which gives you limited access to view discussions

To gain full access to our forums you must register; for a free account. As a registered Guest you will be able to:

Participate in over 40 different forums and search/browse from nearly 3 million posts.

Mrs. S comes down from North Carolina to her 2 million dollar week-end home in Charleston SC. She calls, "No Heat" I arrive and she tells of the main 200 amp on her second panel tripping, the heat breaker sparking, and the computer upstairs doesn't work. "OK I'll look", up the stairs to the attic..... and I stand there for 5 minutes wondering why I am not standing in a bed of coals.

A cheap plastic disconnect was attached to the joist and burnt off, all that's left is the wires and the lugs. It looked as if one of the lugs cracked and sparked.

I serviced this unit in January and checked the connections all tight. My former employer did this install three years ago. Then sold me a portion of the company. This was one of them. I remember thinking at the time of the install, "these are cheap disconnects" and "the electritions are off duty firemen so I guess they are OK". Not again, they get switched or no start up.

It was a 60 amp disconnect pull bar type, with a "v" type spring for the contacts on the pull. It was to the tempstar in the pic, which has 9.6 Kw plus the fan...figure acctual 41.5 amps. The panel breaker was a 50A.

...another item to add to the punch list...

...smoke detector in the attic. Even if I don't have gas up there, electricity can evidently do the job just fine.

Slightly off-topic, I can understand why the circuit breaker did not trip at 50A immediately... takes a while to get to those amperages while everything cooks slowly away. Would a AFCI or GFCI been a better choice. And, for that matter, do they make GFCI's in that size range? (50A, single phase)

The reason the 200 trips is probably do to the location down stream from the fault site. The further away from the fault the main is, the greater the fault will register on the CB. I intentionally faulted a 20 Federal in the vain hope of tripping it while doing a job years ago, too lazy to crawel two hundred feet back out of an attic, and accidently blew an 800 amp main. Did this while I was a journeyman, know better now....LOL There is an electrical formula to show how this occurs.

Originally posted by durango The reason the 200 trips is probably do to the location down stream from the fault site. The further away from the fault the main is, the greater the fault will register on the CB. I intentionally faulted a 20 Federal in the vain hope of tripping it while doing a job years ago, too lazy to crawel two hundred feet back out of an attic, and accidently blew an 800 amp main. Did this while I was a journeyman, know better now....LOL There is an electrical formula to show how this occurs.